docs: def cmServiceRequest(PriorityLevel_presence=0):
      """CM SERVICE REQUEST Section 9.2.9"""
      a = TpPd(pd=0x5)
      b = MessageType(mesType=0x24)  # 00100100
      c = CmServiceTypeAndCiphKeySeqNr()
      e = MobileStationClassmark2()
      f = MobileId()
      packet = a / b / c / e / f
      if PriorityLevel_presence is 1:
          g = PriorityLevelHdr(ieiPL=0x8, eightBitPL=0x0)
          packet = packet / g
      return packet